1s orbital 2s orbital 2p orbitals 3s3s orbital Nucleus Electron energy levels have sublevels of different shapes

3 principles describe the electron configuration of any atom: the aufbau principle the Pauli exclusion principle and Hund’s rule Electron Configurations: location of e – ’s in different orbitals How do electrons fill these orbitals?

End Show Slide 3 of 20 © Copyright Pearson Prentice Hall Electron Arrangement in Atoms > Aufbau Principle: (building up) e – ’s fill orbitals of lowest energy first nucleus

End Show Slide 4 of 20 © Copyright Pearson Prentice Hall Electron Arrangement in Atoms > Pauli Exclusion Principle: (up/down) e – ’s in same orbital have opposite spin nucleus

End Show Slide 5 of 20 © Copyright Pearson Prentice Hall Electron Arrangement in Atoms > Hund’s Rule: (up/up/up/ down/down/down) e – ’s pair after one in each same E orbital nucleus

© Copyright Pearson Prentice Hall Slide 6 of 20 End Show 2s 2 1s 2 3s 2 3p 3 2p 6 Write the electron configuration for phosphorus (P): nucleus

© Copyright Pearson Prentice Hall Slide 7 of 20 End Show Write the electron configuration for phosphorus (P): nucleus 2s22s2 1s21s2 3s23s2 3p33p3 2p62p6 valence electrons: e – ’s in the outer most (highest) energy level How many valence e – ’s in phosphorus (P)? 5

End Show Slide 8 of 20 © Copyright Pearson Prentice Hall Electron Arrangement in Atoms > nucleus Write the electron configuration for Krypton (Kr): 2s 2 1s 2 2p 6 3p 6 3s 2 4p 6 4s 2 3d 10 (3d fills after 4s)

End Show Slide 9 of 20 © Copyright Pearson Prentice Hall Electron Arrangement in Atoms > nucleus Write the electron configuration for Krypton (Kr): 2s 2 1s 2 2p 6 3p 6 3s 2 4p 6 4s 2 3d 10 valence electrons: e – ’s in the outer most (highest) energy level How many valence e – ’s in Krypton (Kr)? 8

4p 1 2s22s2 1s21s2 2p62p6 3p63p6 3s23s2 4p14p1 4s24s2 3d 10 OR 4s 2 [Ar] 3d 10 Write the full electron configuration for Gallium (Ga), atomic number 31. noble gas core configuration Ar

Phosphorus (P): Lewis dot diagram: valence e – ’s as dots [Ne]3s 2 3p 3 1s2 2s2 2p6 3s2 3p31s2 2s2 2p6 3s2 3p3 # valence e – ’s: ___ Group # : ___ 5 5A5A P Lewis dot diagram: Bromine (Br): [Ar]4s 2 3d 10 4p 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 # valence e – ’s: ___ Group # : ___ 7 7A7A Lewis dot diagram: Br valence e – ’s: e – ’s in highest energy level

1.Which element has following electron configuration: 1s 2 2s 2 2p 6 3s 2 A.Ca B.Ne C.Na D.Mg Quick Quiz! How many valence e – ’s? 2 Group 2

2.Write the electron configuration for an atom of oxygen (O). A.1s 2 2s 6 B.1s 2 2p 6 C.1s 2 2s 2 2p 4 D.1s 2 2s 3 2p 3 Quick Quiz. How many valence e – ’s? 6 Group 16 (6A)

H, He Li, Be Na, Mg B, C, N, O, F, Ne Al, Si, P, S, Cl, Ar s orbital p orbitals